The interest of biomolecules, such as proteins, peptides and nucleic acids, has increased dramatically during the past decades. Many drugs are these days based on proteins or peptides, and an increasing number thereof are produced by biotechnological methods using recombinant DNA technology. This kind of methods requires reliable procedures for purification of the product, e.g. from cell debris and undesired substances present in the production system. In addition, studies within the field of proteomics, wherein the function and structure of a protein is explored, also requires purified protein products. The commonly used methods for separation of biomolecules are based either one or both of two principles, namely chromatography and electrophoresis. While chromatography is generally used for preparative purification of biomolecules, electrophoresis is the most powerful technique for analysis of the molecules in crude samples and at various stages of a purification procedure.
In electrophoresis, substances are separated according to their size, or based on differences in pI, as in isoelectric focusing. Polyacrylamide gels are the most widely used in the context of isoelectric focusing, since they have a higher resolving power than e.g. agarose gels. Since the chemical nature of acrylamide renders it unpleasant to handle, precast gels are in general preferred before casting in place. However, the precast gels will need to fulfill certain criteria as regards e.g. stability and shelf life. It is a generally known problem that precast polyacrylamide gels age in alkaline conditions, resulting in a decreased mobility of biological macromolecules therein and also the resolution will deteriorate. The short shelf life of precast polyacrylamide gels is primarily attributed to the hydrolytic degradation of acrylamide moieties in the gel, while the cross-linking units are relatively stable.
WO 97/16462 (Righetti et al) suggests N-mono- and di-substituted hydroxyethoxyethyl-(meth)acrylamides and their analogues in electrophoretic gels. However, it has later been shown that one of the illustrative monomers, denoted HEEAA, tends to auto-polymerise during storage as a 50% aqueous solution at 4° C., even in the presence of a free radical inhibitor. Accordingly, this group of compounds does not fulfill the need of improved and more stable matrix materials.